The prior art is already aware of various attachments between tractors and implements, and these attachments are arranged for the pulling of the implement behind the tractor, and they are also arranged for lifting the implement off the ground for a transport position of the implement. In positioning the implement in a partly raised or even a fully raised and transport position, the prior art encounters a problem of having adequate vertical movement in the lifting members in order to induce sufficient vertical movement of the implement itself, such that the implement can be disposed in a fully raised and thus transport position. That is, it is common practice to use a lift arm mounted on a rock shaft or the like, and once the extending end of the lift arm is in a raised position, say a position substantially above the level of the pivot of the rock shaft itself, then further pivoting of the lift arm will not produce sufficiently significant lifting action for the implement itself. That is, at that end or maximum position of lift effort produced by the lift arm, further rotation of the lift arm creates more horizontal displacement, rather than vertical displacement, of the lifting end of the lift arm, and that fails to produce the desired lifting action of the implement.
Accordingly, the present invention recognizes the aforementioned problem, and it overcomes the problem by providing a tractor implement lift height amplifier which creates maximum lifting effort, and with the lifting effort being substantially in direct proportion to the amount of pivot of the lift arm itself. That is, the present invention provides a lift height amplifier which produces a vertical lifting action even when the lifting arm is itself moving in a substantially horizontal direction at its extending end. In accomplishing this objective, the present invention provides an arrangement of pivotally-connected lift members which interengage to restrict the pivoting action of the members relative to each other when the members are approaching the end of their lifting action, and, at that time, the lifting members interengage each other to alter the length of the effective lift arm and to thereby more nearly translate the additional rotary or pivot action to the vertical lift action.
A further object of this invention is to provide a tractor implement lift height amplifier which can utilize the lift members and the draft arm members and the attachments between the tractor and the implement, all as now in use commercially, and still provide the lift height amplification, accomplished by this invention, in effecting maximum lift for the implement. In accomplishing this objective, the present invention provides a simplified and yet sturdy and reliable type of connection between the tractor and the implement, both for the purpose of draft attachment and lift attachment of the implement to the tractor.
Accordingly, it is the main object of this invention to provide the tractor implement lift height amplifier wherein the pivot action of the lift arm itself is converted to maximum lift effort so that the draft-attached implement behind the tractor can be desirably articularly connected with the tractor but yet can be lifted a maximum distance off the ground, such as for placing the implement in transport position.
Other objects and advantages will become apparent upon reading the following description in light of the accompanying drawings.